Postharvest degradation of microalgae: Effect of temperature and water activity.

摘要

Algal postharvest degradation is an unexplored, yet key component of algalculture. We studied the effects of cold storage, water activity, pasteurization, and heat drying on lipids and protein degradation. Drying to a water activity between 0.90-0.95 aw minimized triglyceride degradation for up to 30 days, but water activities above 0.96 or below 0.90 resulted in a more than 40% triglyceride degradation after 24 hours. Heating above 60° C via either drying oven or pasteurization for 1-3 hours prevented triglyceride conversion to free fatty acids, likely due to the deactivation of lipase. Lipid conversion to free fatty acids at temperatures between 55° C and 40° C averaged 10% per hour. Protein was stable between water activities of 0.45 and 0.99, but degraded 40% during a 60-minute pasteurization at 65° C. Arrest of enzymatic activity is critical to producing a stable algal product.